Jurors at the Casey Anthony murder trial heard testimony on Wednesday from a grief expert who was called by defense attorneys to try to explain how a young mother might respond to the death of her child by partying at bars, getting a tattoo, renting movies, and going on shopping excursions.

Sally Karioth, a professor at Florida State University, said no two people grieve in exactly the same way. She said young adults, like Ms. Anthony, can sometimes be “reluctant grievers.”

The testimony came on the 31st day of the Orlando trial of the Florida mother accused of killing her two-year-old daughter, Caylee. If convicted, Ms. Anthony could face the death penalty.

The testimony is important because it sought to address one of the most perplexing questions raised in the Anthony case. How could a young mother fail to tell her family, friends, and the police about her dead or missing child for 31 days while she partied with friends and acted as if nothing was wrong?

To set up Professor Karioth’s testimony, Defense Attorney Dorothy Sims presented an elaborate hypothetical example which was actually a detailed description of certain factors in Casey Anthony’s life as viewed under the defense theory of the case.

The woman in the hypothetical case was described as a 22-year-old mother of a young child who had a loving bond with the toddler. The woman also lives at home with her parents, who resisted the reality of her unwed pregnancy. Also living in the house was an older brother who was angry for being excluded from any discussion of the pregnancy.

“Add to it that during the 31 days after the child is gone, the mother leaves the home, rents movies, goes shopping, goes to bars, and gets a tattoo that indicated ‘Beautiful Life,’ ” Ms. Sims said.

Karioth said that a young person in such a situation might respond by saying that nothing had happened. They will often engage in risky behaviors, like drinking too much and spending money they don’t have. She added that some hope they can shop their way out of the problem.

Karioth said that people who come from uncommunicative families that don’t talk or feel or share, may engage in denial and what she called “magical thinking.”

As Karioth continued her testimony, Casey Anthony’s eyes turned red. Soon she had a Kleenex out and began dabbing tears away. What made that reaction particularly striking to many observers is that only a few hours earlier she had sat at the defense table cold and expressionless – appearing almost bored – as her father, George Anthony, sobbed on the witness stand while describing his decision to try to kill himself in January 2009 because of his own grief over the loss of his granddaughter, Caylee.

During cross-examination of Karioth, Assistant State Attorney Jeffrey Ashton offered a hypothetical example of his own. In his hypothetical the young mother – within a half day of the child’s death – goes to her boyfriend’s house, rents a movie, spends the night with him, returns secretly to her parents house, and then over the next month doesn’t tell anyone that the child has died or is missing. Then, for the next month, she lies to her mother and her friends by suggesting that the child is with a baby sitter.

“Is that conduct consistent with the type of denial you see in mothers,” Ashton asked.

“I would call that more magical thinking,” Karioth said. “If I can keep all these balls in the air, maybe it won’t be true that I’m fearful may have happened,” she said, suggesting a grieving mother’s possible reasoning.

Ashton asked the professor to consider an additional element to the hypothetical. “Let’s add that the mother deliberately killed the child,” he said.

Sims objected. She told the judge there was no evidence that the mother killed the child.

The exchange underscored the surreal aspect of offering “hypothetical” testimony to a jury that isn’t hypothetical at all.

Karioth said denial can be a coping mechanism.

“For guilt,” Ashton asked.

“It can be,” the professor said.

Ashton then asked about compartmentalization.

“Compartmentalizing traumatic episodes is a typical way of going on with your life,” Karioth explained.

“So one could compartmentalize an unspeakable act, put it in a box, and then go on and act as if nothing happened,” Ashton asked.

Karioth said questions dealing with psychology were beyond her expertise. But she said she has worked with people who engage in “magical thinking.”

She described a mother who had recently lost a child. The mother was concerned because it was dark outside and the weather was turning bad. The little boy had never been in the dark and the rain alone. Karioth said she told the mother she’d be right over. She found a blanket and some umbrellas and sat with the grieving mother until the rain stopped.

“Now that is magical,” she said, “but it is something we needed to do.”

Ashton asked one last question: “You will agree that the bond between a mother and child is hard to break, even with death.”